Oh please, I've seen so many women with short hair being called dikes and lesbians while half the guys in my grade go around sporting long, greasy mullets and no one bats an eye.
I don't think either of them are more or less accepted in or society, it really depends on where you live. Though i have to say, both hair styles are becoming more and more popular in this day and age.
I think a stereotype is also that guys do not take as good care of long hair as most girls, so society views long hair on guys as gross and greasy.
And I agree with MissAwesomeness about the prevalence of the assumption that short hair on women equates lesbianism.